The present invention relates to optionally porous intumescent masses containing carbonization auxilaries, fillers and optionally other auxiliary agents, obtainable by the reaction of isocyanate-reactive compounds, optionally containing phosphorus or boron with polyisocyanates in the presence of polyepoxides.
The intumescent masses according to the invention are distinguished by having surprisingly good fire characteristics in spite of being prepared without the use of special epoxide resin cross-linking agents.
Intumescent masses cross-linked with isocyanates have been known for some time (see DE-OS No. 3 306 698, DE-OS No. 3 302 416 and DE-OS No. 3 109 352). They combine satisfactory intumescence (i.e., formation of a flame-resistant carbonization foam when exposed to fire) with the practical advantage that when the liquid components of the reaction mixture are mixed together they form a relatively highly fluid material which can be applied by pouring or spraying and will then solidify within a matter of minutes, in some cases with the formation of a porous or foamy structure.
Intumescent masses based on epoxide resins, in particular on epoxide resin formulations which are hardened with amines, i.e., cold setting epoxide resin formulations, are also known (see DE-OS No. 3 303 702). The intumescence of such materials ranges from moderate to good, but the materials are particularly distinguished by the fact that the intumescent foam obtained from them has a high resistance to flame erosion, i.e., it is sufficiently solid to afford the necessary resistance to the oxidative and especially the mechanical stresses produced by the impact of burning gases at high temperatures and to ensure good or very good protection against the passage of heat.
At the same time, cold setting epoxide resins have such a long pot life i.e., the reaction mixture remains fluid for such a long time, that reaction mixtures which are sprayed at room temperature can only be applied in relatively thin layers to surfaces such as wall surfaces without running or dripping. It would be desirable to have an intumescent material which combines the good fire characteristics of epoxide resin intumescent masses with the advantages, for the purposes of practical application, of solidifying in the same manner as intumescent masses which are cross-linked with isocyanates.
Since the aminic hardeners of epoxide resin masses react instantly with isocyanates, it is not possible to use a combination of the two systems.